Plant Succession on Former Tidal Lands in the Northeastern Polder

The area to be discussed in this article was formed along the dikes of the former Zuidersea. In times past year after year the sea deposited its material along the shore and finally new land came into being. It is not known, however, when this took place, nor if the process was enhanced by man by means of plantations of Schoenoplectus lacustris, as was the case on the nearby Island of Kampen. Nowadays the area is considered to be the “hay barn” of the adjacent region and it is well established that these coastal lands have been under cultivation for several decennia. Before the construction of the enclosing dam of the Zuidersea, these offshore lands were frequently flooded, since they were protected only against high water levels by low summer dikes. These inundations occurred mainly during winter, but occasionally also in summer when strong gale floods overflowed the area. In this way much silt was deposited, acting as a natural fertilizer. A luxuriant but predominantly saline vegetation developed, in which Juncus gerardi dominated to such an extent that people characterised the cover as a “heavy grass sod.”